Method and apparatus for forming combustion gas mixtures for rotary piston engines



5 1 9 t w 0 h 0 m 3 w N h m S T M3 N UT. B G WN C E MING ISTON S. MEURERFOR Y P Aug. 17, 1965 M OD AND APPARATUS S MIXTURES FOR R0 OriginalFiled April 21, 1961 gwuv/wtw jLe nLed Megmca 1955 s. MEURER MET ANDAPPARATUS FOR FORMING G 3 FOR ROTARY PISTON Original Filed April 213,200,795 COMBUSTION ENGINES 3 Sheets-Sheet 2 MIXTURE 1961 Aug. 17, 1965s. MEURER 3,200,795 METHOD AND APPARATUS FOR FORMING COMBUSTION GASMIXTURES FOR ROTARY PISTON ENGINES Original Filed April 21. 1961 SSheets-Sheet 3 5 6 7 27 28 2s 25 f 25 K m H In 1/ .2 ,2 "2

niig mwwk xpgtwm United States Patent C) 3,209,795 METHGD AND APEARATUSFGR FGRMENG COM- EUSaTi-DN GAS MIXTURES FOR ROTARY PTSTON ENGINESSiegfried Meurer, Nurnherg, Germany, assignor to MaschinenfabrikAugshurg-Nurnherg A.G., Nurnherg, Germany Original application Apr. 21,1961, Ser. No. 104,621, now Patent No. 3,144,006, dated Aug. 11, 1964.Divided and this application Mar. 11, 1964, Ser. No. 375,9?1 Claimspriority, application Germany, Apr. 30, 1969, M 45,163 6 Claims. (Cl.123-8) This application is a division of application Serial Numher1G4,621, filed April 21, 1961, now granted as U.S. Patent No. 3,144,006,dated August 11, 1964.

This invention relates to rotary piston internal combustion engines and,in particular, to the formation of the combustion gas mixture for suchengines.

This invention is further directed to the compression of the fuel andair mixture and its combustion in rotary or turning piston engines insuch a way that the most favorable thermal conditions are produced. Inthis case, the peculiarities of a rotary piston engine must be takeninto account as it is not possible, for example, to raise thecompression ratio at will without affecting other important structuraldimensions such as those that influence the volume of gas and the enginesize. It is especially desirable to keep the maximum gas pressure as lowas possible in order to keep the bearing pressures within reasonablevalues with respect to the large piston surface and the working volume.In order to improve the effective thermal conditions, it is necessary onone hand to raise the compression ratio, while on the other hand tocontrol the engine performance in an even number of turns so that withpartial loading the excess of air increases and the mixture ratiobecomes leaner, as compared to the Otto-method in which the mixtureratio remains constant or varies only within narrow limits so that itdoes not fall outside the ignition limit of the combustion gas.

It is known to use the latter kind of solutions as variations in theloading of reciprocating engines. Their effect for the consumption of apartial loading is present in every compression ratio whether high orlow. The best consumptions are achieved theoretically betweencompression ratios which almost correspond to those of fast runningreciprocating piston diesel engines. lowever, in rotary piston engines,one is often interested, for constructural reasons, to not use acompression ratio that is too high and therefor, under certainconditions, dispense with self-ignition without having to give up theadvantage of regulating the quality of the combustion gas mixture.

From the manner of forming the combustion gas mixture and the method ofburning the mixture in reciprocating piston diesel engines, it is knownthat it is difficult to guarantee the obtaining of a complete combustionin which, at first and after the beginning of the ignition, releasesonly small quantities of heat together with a low speed in the rise ofthe gas pressure, while the quantity of heat which is released is raisedup to the maximum with each degree of crank shaft rotation to the end ofthe combustion of the gases and completion of the expansion. Such acombustion, however, is necessary in order to meet the constructionalpeculiarities of a rotary piston engine. Such is accomplished by thisinvention. This has been done with the object of avoiding spontaneousself-ignition reactions which are created by the injection of atomizedliquid fuel into hot compressed air and to obtain a gradual mixture ofthe vaporized fuel with the combustion air. It has been found that, toget snares Patented Aug. 17,1965

a rapid vaporization of the fuel, combustion chamber surfaces whosetemperatures are suited to the peculiarity of the fuel being used aremost desirable. The most favorable temperature for a fuel corresponds toa molecular composition of C H is 340 C. Temperatures of this order canbe produced on the surface of a piston in a rotary piston engine.

According to this invention, the piston is provided with a porous orperforated surface which is sprayed with fuel on its side directed awayfrom the combustion chamber or the piston cylinder space. The fuel is:distributed under the force of the peripheral acceleration of therotating piston and on the other hand under the centrifugal forces whichare created by the rotating piston and which have the tendency to flingthe liquid fuel outwardly in the direction of the piston cylinder space.The porous surface serves to hold the liquid fuel against thecentrifugal forces and to ensure that only the vapors formed in the hotsurface by reason of the large surface area of the perforations reachoutwardly of the piston. Furthermore, since two combustion chambers arecreated during the rotation of the rotary piston, of which the oneleading in the rotation increases in volume from zero to maximum whilethe one trailing in rotation decreases from maximum to zero, and sinceboth chambers are separated from each other by the constriction orsaddle point of the trochoid shape of the piston space, there is createda strong air flow at the point of constriction when changing over fromone combustion chamber to the other, and the air flow must use theperforations in the porous surface because of the lack of any otherconnecting channels between the two partial combustion chambers, andwhen the air passes through this porous surface, an intensivevaporization of the fuel and mixing with the air takes place which iscontinued with the rotation of the piston beyond that local point. Theporous surface in this sense forms a very effective surface vaporizerwhich is built into the piston and which effects the necessaryvaporization and mixing of the fuel. For the successful cold starting ofan engine, it is expedient to use a source of ignition for thecombustion gas and so a further reduction in the compression ratio maybe used. Such source of ignition is either in the form of an electricspark or a hot point, the effectiveness of which can be increased bycatalytic means.

The porous surface for enhancing the combustion of the gas is a porousplate composed of a coarse porous material. When using c'hromoxide or acoating of chromoxide over a body of ceramic material or when othereffective metallic materials are used for the porous plate, the reactionprocess is advantageously influenced with regard to the reaction productas well as the speed of reaction to achieve a high degree of combustionwith little waste.

The means by which the objects of the invention are obtained aredescribed with respect to the following drawings which are directed to atwo-thirds rotary piston engine, but the principles of which can beapplied by analogy to other rotary or turning piston engine constructedin the manner of a trochoid.

FIGURE 1 is a cross-sectional view through a twothirds rotary pistonengine and showing the section through the porous plates inserted in thesurface of the piston;

FIGURE 2 is a similar view showing the piston turned to anotherposition;

FIGURE 3 is a similar view of a modified form of the invention;

FIGURE 4 is a similar view of a further modified form of the invention;

FIGURE 5 is a transverse cross-sectional view of a portion of thepiston;

FIGURES 6 and 7 are similar views of two respective modifications ofFIGURE and FIGURE 3 is a plan view of a piston according to thisinvention.

As shown in FIGURE 1, the cylinder housing 1 has a trochoid shapedpiston cylinder space within which piston 2 is rotatably mounted.Exhaust gas port 4 and intake air port 5 communicate with the cylinderspace. Piston 2 has three piston head surfaces 6, '7 and 8 which facethe cylinder space, with the piston rotating in the direction of thearrow 9. According to this invention, porous piston head surfaces areformed by means of plates 10 inserted in each piston head surface with achannel 1 being formed between the plate id and the body of the piston2. Channel 11 can increase in size from its trailing end 1.7; openinginto compression chamber 13 toward its leading end 14 which opensthrough the piston head to receive fuel from the injection nozzle 15.Preferably, the fuel is injected as a solid jet of fuel. The trochoidshaped piston cylinder space is narrowed at its constriction or saddlepoint 17 which constitutes a sealing means.

In FIGURE 2, the leading partial combustion chamber 16 is formed whenthe piston of FIGURE 1 is rotated counterclockwise. An air flow shown bythe arrows 13 is created between chamber 13 and chamber 16. The sparkplug or hot point ignition means are indicated by the arrows 19 or 20.The surface of the piston has a slightly flattened portion 21 in theplate lit for clearing the constriction 17.

As shown in FIGURE 3, the channel 11 of piston 2 is provided with a port22'; forming an opening through the side of the channel for theintroduction of the liquid fuel, this opening being below the outersurface of the plate lit.

in the madification of FIGURE 4, the fuel inlet port 23 extendintermediate the leading and trailing ends of plate it the fuel beingdeposited through port 23 onto a deflecting protuberance 24. FIGURE 5shows the channel '11 in piston 2 having a kidney shape which forms sidesub-chambers 25 and the opening 26 into the outside of the piston.

FIGURE 6 is a modification of FIGURE 5 inv which the channel is openedexteriorly of the piston through openings 27 and in the modification ofFIGURE 7 each of the two channels 111 is provided with openings 28 and29, respectively. In FIGURE 8, the plate 10 is shown mounted in a cavityformed in the surface of the piston body.

Fuel nozzles for the injection of fuel into a diesel engine ordinarilyhave the nozzle bore and the nozzlc'needle arranged within the body ofthe nozzle. In this invention, in order to be in accord with thepeculiarities of a rotating piston engine, the ordinary construction ismodified. In this invention, note FIGURE 1, the bore a for the injectionnozzle is drilled directly through the housing 1 to form the openinginto the cylinder space. The nozzle needle for the injection nozzle ismounted in the bore 15a either without any further attachment or, asheretofore, is mounted in a separate nozzle body. This construction hasthe advantage that the sliding of the sealing strip 3 in the apex of thepiston over the bore 15a can take place smoothly and without beingdeviated by a nozzle body screwed in the housing from the outside.

When the wall of the cylinder contains bores or indentations, the riskexists that, at the moment the sealing strip passes over such bores orindentations, the working gases in the cylinder which are underdifferent pressures on the leading and trailing sides of the sealingstrip create strong air currents which lead to the injury of the sealingstrip or to difficulties with the bores or indentations. The differencein pressure'on opposite sides of the sealing strip is equal to zero orapproximately zero when the rotating piston is in certain positions andaccording to the compression of the working phase in adajacent chambers.Such a piston position is shown approximately in FIGURE 1 in which thechamber 13 is in the state of compression while the chamber 15a is beingemptied due to the opening of exhaust port 4. In this phase, thepressure difference at the sealing strip 3 is zero. Consequently, it isunderstandable that this is the most favorable moment for the sealingstrip 3 to pass over a bore or indentation in the wall of the cylindersince at this moment there is no gas motion.

The function of the apparatus of this invention for the forming of acombustion gas mixture is as follows:

In FIGURE 1, when the piston moves in the counterclockwise direction ofarrow 9, the air in chamber 13 is being increasingly compressed. Thevelocity of the sealing strip at this moment is still close to itsminimum. When the opening Ma of channel 11 reaches the range of the bore15a, injection of fuel from the nozzle 15 begins and the fuel movesthrough the length of channel 11. The solid liquid fuel is injected inthe same manner as used in the injection of fuel into reciprocatingdiesel or Otto engines. The form of the jet and the injection pressureare as required by the particular engine. Because of the velocity of theinjected fuel caused by the injection pressure, the fuel tends to runthrough channel 11 toward the trailing end opening 12. Since the pistonturns in the direction of arrow 9, the movement of the fuel towardopening 12 is assisted by the rotation of the piston. Furtherdistribution of the fuel is successfully accomplished by fully using theintertia of the fuel, by reason of which the fuel injection throughnozzle 15 is effected with very low pressures and low velocity of fuelinjection but with a large cross-sectional area for the jet. By soinjecting the fuel, it can be said that in effect the channel 11 ispushed over the injected fuel by the rotation of the piston.

As the piston continues to turn, the fuel takes the velocity of thepiston so that it becomes subject to the then applied centrifugal force.Such force drives the fuel through the porous body It VHPOIIZBS thefuel, and then passes the fuel into the chamber 13. By this means andeven with a small radial extension of the wall of the combustionchamber, the fuel is prevented from reaching the cooled wall of thechamber in liquid form.

The further formation of the combustion gas mixture is as follows:

As shown in FIGURE 2, the piston 2 lies immediately before the maximumair compression in chamber 13. Because of the particular trochoid shapeof the cylinder space wall, two partial chambers 13 and 16 nOW exist. Astrong air flow is created at the constriction 17 of the trochoid wallsince the air is being pushed from chamber 13 which is decreasing involume into chamber 16 which a is increasing in volume. Therefore, theair is forced to flow partially through the porous plate it as shown bythe arrows 18 so that there is an intensive mixing of the air with thefuel that has been vaporized in the porous plate 3.0. A part of the fuelis being ejected through the trailing end 12 of channel 11 and due tothe centrifugal force is projected from the surface of plate 16 intochamber 13 so that a formation of a gas and fuel mixture also takesplace in chamber 13. Burning of the fuel is initiated by the aircompression'tempera'ture in chamber 13 or by means of another source ofignition 19 so that the movement of the gases through the porous surfaceit) and channel It continues to increase until combustion begins inchamber 16. Now when a second source of ignition 29 is used whose effectof ignition with regard to time is started before, at the time with, orafter that of the ignition source 19, the operation of the gas flow atconstriction 17 can be regulated as desired. Upon the further turning ofthe piston, the porous surface of plate 10 is covered with thecombustion mixture forming gas stream along its entire length. Theperipheral length between the leading and trailing ends of the surfaceof plate 10 makes possible a very favorable distribution of thecombustion gas mixture in the whole of the elongated combined combustionchambers I3 and I6 and makes it possible to obtain the required slowrelease of heat as desired. By the flattened portion 21 of the surfaceof plate 1%, the velocities of the air and fuel stream can be variedwith regard to time and space and by so doing it is possible to avoidlarge interior losses due to throttling. The transverse width of thesurface of plate re in the direction of the axis of the crank shaft canbe varied in order to give definite zones of the combustion chamber asupply of more or less fuel. This can be assisted in the shaping ofchannel 11, especially in its radial and axial directions.

Injection of the fuel can also be accomplished as illustrated in FIGURES3 and 4-.

As shown in FIGURE 3, the fuel is injected into channel 11 adjacent thesealing strip and parallel to the axis of the crank shaft and below theouter surface of plate Iii. In the position of piston 2 shown in FIGURE3, the sealing strip is passing through its minimum peripheral velocity.This moment is preferably used for the introduction of the fuel intochannel 11 beneath the the porous plate It In so doing, the fuel can beinjected into opening 22 with very little pressure and through the sideWall of the housing I for the piston cylinder. As the piston turns inthe direction of the arrow 9, the fuel is distributed along channel Illand through plate It) as heretofore described.

In FIGURE 4, the fuel is introduced intermediate the leading andtrailing ends of plate It). The fuel nozzle is mounted in theconstriction of the trochoid wall and an opening 23 in plate It servesfor introducing the oil into channel Ill. The fuel entering throughopening 23 is distributed into the channel by impingement on deflect ingridge 24.

FIGURE 5 is a modified construction for the distribution of the fuel.This fuel shows a cross-sectional view transversely of the piston andparallel to the crank shaft. The channel 11 is formed in the body ofrotary piston 2 and has a cross-section in the shape of a kidney for thepurpose of forming a fuel collecting groove such that the fuel has beeninjected as described for FIGURES 1, 3 and 4 and is distributed throughchannel 11 by the turning of the piston. The fuel cannot, however, beflung from the groove by centrifugal force as the fuel is contained inthe chambers 25. As described for FIGURE 2, the fuel is vaporized andmixed with the compressed air which enters opening 26 with the fuel andoil so mixed then flowing into chambers 13 and 16. In this modification,the openings 26 can be formed as a continuous slit or as a plurality ofspaced slits or by means of a number of circular connecting bores.

The distribution of the openings transversely of the piston, that is inthe direction of the axis of the crank shaft is accomplished by theslits 27 of FIGURE 6 or by the making of a plurality of channels 11,each of which has its individual openings. According to how the fuel isto be distributed from the piston, the openings from the piston tochambers 13 and 16 are given the form of the ports 28 or 29. Theinclined opening 28 is provided when greater amounts of fuel are usedand when a later discharge of the fuel is desired, while in the zones inwhich an early discharge is to take place, the bore 29 iscorrespondingly used. By these means, it is possible to achieve adistribution of fuel along the periphery of the piston which correspondsto the distribution of the air and the requirements of the fuel-airmixture for the combustion gas with regard to time.

In the drawings, the dimensions of the size of the channels and openingsare exaggerated for purposes of clarity. As shown in FIGURE 8, in apractical construction, the rear surface of the plate It) is providedwith ribs which form the channel Ill when the plate is inserted in thepiston surface. By using an inserted plate, the degree of the ribcontact with the body of the piston can be such so as to keep thetemperature of the heat conducting bodies to the values that result inthe greatest rapidity of vaporization for the fuels being utilized.

Having now described the means by which the objects of the invention areobtained,

I claim:

I. In a rotary piston engine having an equilateral arc triangular pistonmounted for rotation in a trochoid shaped piston cylinder, said pistonhaving a combustion gas forming structure comprising a gas permeablesurface area composed of a body containing a plurality of slits on saidpiston facing into said cylinder, channel means beneath said surfacearea, and nozzle means for injecting fuel into said channel means forvaporizing the fuel in conjunction with said surface area and forcingthe vaporized fuel through said surface area and through said channelmeans to mix the vaporized fuel and air into the combustion gas.

2. In a rotary piston engine having an equilateral arc triangular pistonmounted for rotation in a trochoid shaped piston cylinder, said pistonhaving a combustion gas forming structure comprising at least onechannel in said piston extending substantially parallel to and beneaththe outer surface of said piston, nozzle means for injecting fuel intosaid channel for heating and vaporizing fuel in said chan nel, andopening means of substantially lesser Width than said channel,communicating said channel and said cylinder radially outward of saidpiston surface for conducting compressed air from said cylinder intosaid channel for mixing with the vaporized fuel and forming thecombustion gas.

3. In an engine as in claim 2, said channel having a kidney shapedcross-section, and said opening means being positioned so that fuelunder the centrifugal force of a rotating piston is substantiallyprevented from leaving said channel through said opening means.

4. In an engine as in claim 2, said opening means comprising slitsarranged along the length of said channel.

5. In an engine as in claim 2, said opening means further comprising anopening at the trailing end of said channel with respect to thedirection of the rotation of said piston.

6. In an engine as in claim 2, said opening means being contained in aplate secured to said pistion, and ribs on said plate for forming saidchannel.

References Cited by the Examiner UNITED STATES PATENTS 10/59 Meurer eta1. 12332.2 8/60 Froede 123--8 OTHER REFERENCES KARL J. ALBRECHT,Primary Examiner. JOSEPH H. BRANSON, JR., Examiner.

1. IN A ROTARY PISTON ENGINE HAVING AN EQUILATERAL ARC TRIANGULAR PISTONMOUNTED FOR ROTATION IN A TROCHOID SHAPED PISTON CYLINDER, SAID PISTONHAVING A COMBUSTION GAS FORMING STRUCTURE COMPRISING A GAS PERMEABLESURFACE AREA COMPOSED OF A BODY CONTAINING A PLURALITY OF SLITS ON SAIDPISTON FACING INTO SAID CHAMBER, CHANNEL MEANS BENEATH SAID SURFACEAREA, AND NOZZLE MEANS FOR INJECTING FUEL INTO SAID CHANNEL MEANS FORVAPORIZING THE FUEL IN CONJUNCTION WITH SAID SURFACE AREA AND FORCINGTHE VAPORIZED FUEL THROUGH SAID SURFACE AREA AND THROUGH SAID CHANNELMEANS TO MIX THE VAPORIZED FUEL AND AIR INTO THE COMBUSTION GAS.